1. Field of the Invention
The invention relates to a method of cleaning industrial plant components to remove silanes, metal halides and organometallic halides, using a nitrile or amine.
2. Background Art
Many crude industrial products and industrial product mixtures, such as direct synthesis (Müller-Rochow synthesis) mixtures, comprising chlorosilanes and methylchlorosilanes, or the chlorosilane mixtures obtained from hydrochlorination of metallurgical silicon, may comprise silanes, metal halides and organometallic halides, particularly AlCl3. The silanes present in the crude silanes are separated into pure silanes by multi-stage distillation. The aforementioned impurities in the crude silanes form deposits in the pipes causing problems which may even culminate in blockage of the lines. The lines thus require dismantling and cleaning, e.g. with water, at regular intervals. This method of cleaning has two disadvantages. The first is cost and inconvenience. Disassembly, cleaning and reassembly of lines is costly and very time consuming. The second disadvantage of cleaning with water is the formation, by hydrolysis of chlorosilane residues, metal chlorides, and/or organometallic halides and/or mixtures of metal halides/organometallic halides, of hydrochloric acid which attacks the pipes. Acetonitrile is described as a solvent for aluminum chloride [Zeitschrift für anorganische und allgemeine Chemie. Weinheim: Wiley-VCH, ISSN 0372-7874 Vol. 511 (4. 1984), p. 148].